Відповідь:

1. Tim has won the Pancake Day race three times before.
2. This is the best event I have ever been to.
3. She hasn't been to the parade for years.
4. I've just come back from Sue's graduation.
5. I have been really busy so far, arranging next week's event.
6. I have never been to the Book Fair, but I want to go next year.
7. I haven't participated in this contest since 2011.
8. Have you opened your presents yet?